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!!! able to finish my 80m four square array. The array uses four FORCE12 #EF-180BV verticals with a Comtek Systems phasing box. Each vertival uses four 1/4 wavelength radials elevated about 8 feet above ground. The array is installed in a wooded area and some of the nearby trees are in the 60 foot range. Having read the FORCE12 EF-180BV advanced installation notes, I tuned pairs of radials for 3.660 MHz and then each antenna for the same. Based on the installation notes I expected the array to shift up to around 3.790 MHz but it barely shifted at all. I retuned each antenna to around 3.790 MHz and the array then resonated at 3.812 - 3.822 MHz (depending on direction) with about a 5% power dump. Saturday afternoon (one hour before sunset) I began testing and worked G0NVD. He was S9 off the front of the array dropping to S5 (barely above the noise level) off the back. I'm told this equates to about 20 dB F/B. Comparisions with KC1XX who uses a pair of quads up 200+ feet were that he was about 10 dB louder then I was with comparable output power. Sounds like everything is working well. Sunday I decided to fine tune the array so that it resonated below 3.800 MHz rather than above it. The fine tuning process was difficult and at times I wondered if I was doing more harm then good. In the end the array resonates between 3.793 and 3.797 MHz and shifted up 24 - 30 KHz. The final test data is below. DIRECTION Fr (single ant) Fr (array) DUMP PWR. Fr SHIFT NE 3.764 MHz 3.794 MHz 3.0 % 30 KHz SE 3.769 MHz 3.793 MHz 5.0 % 24 KHz SW 3.770 MHz 3.794 MHz 2.5 % 24 KHz NW 3.764 MHz 3.797 MHz 4.5 % 26 KHz Special thanks go to Jim Fisher VE1JF, Jim K4SQR, and Tom N6BT for their technical support and encouragement. I recommend anyone putting up a four square up to consider using a Comtek box. Les Peters, N1SV -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 Submissions: send to Force12Talk@qth.com To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk For problems with the list, contact n4zr@qth.com |